Temperature dependence of narrow-band terahertz generation from periodically poled lithium niobate

Femtosecond optical pulses are used to generate narrow-band terahertz wave forms via optical rectification in a periodically poled lithium niobate cry stal. By cooling the crystal to reduce losses due to phonon absorption, we are able to obtain bandwidths as narrow as 18 GHz at a carrier frequency of 1.8 THz. Temperature-dependent measurements show insignificant bandwidth b roadening between 10 and 120 K, although the terahertz power substantially decreases as the temperature increases. Absolute power measurements indicat e a conversion efficiency of at least 10(-5). (C) 2000 American Institute o f Physics. [S0003-6951(00)01735-6].